Methods and apparatus for heat treatment and sand removal for castings

ABSTRACT

A system and method for heat treating castings and removing sand cores therefrom. The castings are initially located in indexed positions with their x, y, and z coordinates known. The castings are passed through a heat treatment station typically having a series of nozzles mounted in preset positions corresponding to the known indexed positions of the castings passing through the heat treatment station. The nozzles apply fluid to the castings for heat treating the castings and degrading the sand cores for removal from the castings.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of co-pending U.S. patentapplication Ser. No. 11/076,091, filed Mar. 9, 2005, which is acontinuation of U.S. patent application Ser. No. 10/636,367, filed Aug.7, 2003, now U.S. Pat. No. 6,910,522, that issued on Jun. 28, 2005,which is a continuation-in-part of U.S. patent application Ser. No.10/066,383, filed Jan. 31, 2002, now U.S. Pat. No. 6,672,367, thatissued on Jan. 6, 2004, which claims priority to U.S. ProvisionalApplication Ser. No. 60/266,357, filed Feb. 2, 2001, which is acontinuation-in-part of U.S. patent application Ser. No. 09/665,354,filed Sep. 19, 2000, now abandoned, which is a continuation-in-part ofU.S. patent application Ser. No. 09/627,109, filed Jul. 27, 2000, nowabandoned, which claims priority to U.S. Provisional Application Ser.No. 60/146,390, filed Jul. 29, 1999, U.S. Provisional Application Ser.No. 60/150,901, filed Aug. 26, 1999, and U.S. Provisional ApplicationSer. No. 60/202,741, filed May 10, 2000. This application further claimspriority to U.S. Provisional Application Ser. No. 60/401,969, filed Aug.8, 2002. Each of the above-noted applications is incorporated byreference in their entirety.

TECHNICAL FIELD

This invention generally relates to metallurgical casting processes, andmore specifically to a method and apparatus for removal of a sand corefrom a casting and the heat treatment of the casting.

BACKGROUND OF THE INVENTION

A traditional casting process for forming metal castings employs one ofvarious types of molds for example, a green sand mold, a precision sandmold, or a steel die, having the exterior features of a desired casting,such as a cylinder head or engine block, formed on its interiorsurfaces. A sand core comprised of sand and a suitable binder materialand defining the interior features of the casting is placed within themold or die. Sand cores generally are used to produce contours andinterior features within the metal castings, and the removal andreclaiming of the sand materials of the cores from the castings afterthe casting process is completed is a necessity. Depending upon theapplication, the binder for the sand core and/or sand mold, if used, maycomprise a phenolic resin binder, a phenolic urethane “cold box” binder,or other suitable organic binder material. The mold or die is thenfilled with a molten metallic alloy. When the alloy has solidified, thecasting generally is removed from the mold or die and may be then movedto a treatment furnace(s) for heat-treating, reclamation of the sandfrom the sand cores, and, at times, aging. Heat treating and aging areprocesses that condition metallic alloys so that they will be providedwith different physical properties suited for different applications.

In accordance with some of the prior art, once the casting is formed,several distinctly different steps generally must be carried out inorder to heat treat the metal casting and reclaim sufficiently pure sandfrom the sand core. A first step separates portions of sand core fromthe casting. The sand core is typically separated from the casting byone or a combination of means. For example, sand may be chiseled awayfrom the casting or the casting may be physically shaken or vibrated tobreak-up the sand core and remove the sand.

Once the sand is removed from the casting, heat treating and aging ofthe casting generally are carried out in subsequent steps. The castingis typically heat treated if it is desirable to, among other treatments,strengthen or harden the casting or to relieve internal stresses in thecasting. An additional step consists of purifying the sand that wasseparated from the casting, including burning the binder that coats thesand, abrading the sand, and passing portions of the sand throughscreens. Therefore, portions of sand may be re-subjected to reclaimingprocesses until sufficiently pure sand is reclaimed.

There is, therefore, a desire in the industry to enhance the process ofheat treating castings and reclaiming sand core materials therefrom suchthat a continuing need exists for a more efficient method, andassociated apparatus, that allow for more efficient heat treatment, sandcore removal, and reclamation of sufficiently pure sand from the sandcore.

SUMMARY OF THE INVENTION

Briefly described, the present invention comprises a system and methodfor heat treating castings, such as for use in a metallurgical plant,and for removing the sand cores used during the casting processes. Thepresent invention encompasses multiple embodiments for efficientlyremoving and reclaiming the sand of sand cores using fluid streamscomprising one or more fluids that degrade the cores. In addition tosand and other suitable filler materials, the cores comprise bindermaterials that can be soluble in one or more fluids contained in thefluid streams used in the process and directed at or into the castings.When the cores are exposed to the fluid, the binder tends to dissolveand the core degrades.

In one embodiment of the present invention for sand core removal andheat treatment of castings, a molten material, such as aluminum or othermetal, is poured into molds or dies. The temperature of the molds ordies can be adjusted, either by heating or cooling, prior to the pouringof the molten material therein in order to make the casting process moreefficient. The molds or dies may be preheated to maintain thetemperature of the metal close to a heat treatment temperature as thecastings are formed in the molds. The castings are then removed fromtheir molds and are each placed in a pre-defined position on a saddlethat has known x, y and z coordinates. Each saddle generally isconfigured to receive one or more castings in a fixed orientation orposition with the x, y, and z coordinates of each casting located in aknown, indexed position or orientation so that the core apertures of thecastings formed by the sand cores are oriented or aligned in known,indexed positions. The saddles further can include locating devices toguide and help maintain the castings in their desired; known indexedposition.

Each saddle, with at least one casting positioned therein, is movedthrough a heat treatment furnace or chamber of a heat treatment stationfor heat treatment and core removal, and also potentially thereclamation of the sand cores. While passing through the heat treatmentstation for heat treatment, a series of nozzles with x, y and zcoordinates that are fixed or aligned with the position of castingsdirect streams of one or more fluids, such as steam, water, air, oils,organic solvents and combinations thereof, onto and into the castings.The fluid flows tend to degrade, dislodge and aid in removal of the sandof the sand cores from the internal cavities of the castings as the sandcores are broken down in the heat treatment station, in part bydissolving the binder which can be soluble in one or more components ofthe fluid stream. Typically, the nozzles are arranged in a series ofnozzle stations positioned sequentially through the heat treatmentchamber, with the nozzles of each nozzle station oriented in apre-defined arrangement corresponding to the known positions of the coreapertures of the castings, and each nozzle assembly can be controlledremotely through a control system or station.

In another embodiment of the invention, the castings can be left intheir molds or dies for “in-die” or “in-mold” heat treatment of thecastings. The molds or dies typically are pre-heated before the moltenmetal of the castings is poured into them to maintain the metal close toa heat treatment temperature for the castings, so as to at leastpartially heat treat the castings inside the dies while and after thecastings solidify. Thereafter, the molds or dies, with their castingstherein, typically are located or placed in indexed orientations orpositions with their x, y and z coordinates known for pre-heating and/orheat treating of the castings therein and removal of the sand cores.

For heat treatment and the removal and reclamation of the sand cores ofthe castings, the castings and sometimes the molds or dies generally arepassed through a heat treatment furnace of a heat treatment station. Theheat treatment station further includes a plurality of nozzle stationseach having a series of nozzles oriented or positioned in a pre-definedmanner corresponding to the known positions of the molds or dies andcastings for applying high pressure fluids thereto. The nozzle stationsalso can include robotically operated nozzles that move along apre-defined path around the molds or dies, into various applicationpositions corresponding to the positions or orientations of accessopenings or apertures in the molds or dies for access to the castingsfor dislodging the sand cores from the castings. The heat treatmentstation also can include alternative energy sources, such as inductiveor radiant energy sources, or a heated oxygen chamber or a heatedfluidized bed, for supplying energy to the dies or mold packs to raisetheir temperature for heat treating the castings therewithin.

Thereafter, the castings are removed from their molds or dies and arepassed through subsequent core removal stations or processes to furtherremove and potentially reclaim the sand cores from the castings.

In a further embodiment, the molds or dies are pre-heated to apre-defined temperature. Thereafter, as molten metal is poured into thedies, the dies continue to be heated to heat treat castings as they aresolidified without removing the castings from the dies. The dies canthen be transferred to a quenching station for quenching of the castingsand removal of the sand cores therefrom. In this embodiment, the diesgenerally are maintained in a known, fixed position or orientation at oradjacent the pouring station. The dies are heated by the application ofheated fluids from a series of nozzles positioned about the dies,typically in alignment with die access openings thereof. The nozzlesfurther are subsequently moved about the dies between a series of nozzlepositions set according to the position or orientation of the dies, forheating the dies to heat treat the castings within the dies.Alternately, the mold or die may be placed, at least partially, in atemperature-controlled fluid bed for heating or otherwise controllingthe mold or die temperature for heat treating the castings and possiblyaccomplishing other purposes.

In yet another embodiment, the casting is pre-heated, either within themold or with the mold removed, at a pre-heating station in order toadjust the temperature of the casting to approach or reach theappropriate heat treatment temperature range prior to actual heattreatment. One or more fluid streams can be directed at or into thecasting during pre-heating or at the pre-heating station in order toheat the casting and/or degrade the core contained therein. The castingmay be placed in an indexed position with the fluid stream(s) beingsupplied from one or more nozzles adjusted to direct the fluid streamsat or into the casting. The casting is then transferred to a heattreatment station for heat treating and onto further processing.

Various objects, features, and advantages of the present invention willbecome apparent upon reading and understanding this specification, takenin conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration of a first embodiment of the presentinvention.

FIG. 2 is a side elevational view illustrating introduction of moltenmetal into a mold.

FIG. 3 is a perspective view illustrating the positioning of castingswithin a saddle.

FIG. 4 is a schematic illustration of a further embodiment of thepresent invention for in-mold heat treating with core removal.

FIGS. 5A-5B are side elevational views illustrating movement of thenozzles to various application positions about a mold or die for in-moldheat treatment and/or core degrading.

FIG. 6 is a side elevational view schematically illustrating analternative embodiment of a heating chamber for in-mold heat treatmentof castings.

FIG. 7 is a side elevational view schematically illustrating anotheralternative embodiment of a heating chamber for in-mold heat treatmentof castings.

FIGS. 8A-8C are side elevational views schematically illustratingfurther alternative embodiments of heating chambers for in-mold heattreatment of castings.

FIG. 9 illustrates an additional embodiment of a heat treatment unitincluding the various embodiments of heating chambers shown in FIGS.6-8C, positioned in series.

FIG. 10A is a schematic illustration of a further embodiment of thepresent invention for processing metal castings.

FIG. 10B is a side elevational view of the heat treatment line of the 10embodiment of the present invention of FIG. 10A.

DETAILED DESCRIPTION OF ME INVENTION

Referring now in greater detail to the drawings in which like numeralsrefer to like parts throughout the several views, FIG. 1 generallyillustrates a metallurgical casting process 10. Casting processes arewell known to those skilled in the art, and a traditional castingprocess will be described only briefly for reference purposes. Itfurther will be understood by those skilled in the art that the presentinvention can be used with any type of casting process, including theformation of castings formed from aluminum, iron and various other typesof metals and/or metal alloys.

As illustrated in FIGS. 1 and 2, according to the present invention, amolten metal or metallic alloy M is poured into a mold or die 11 at apouring or casting station 12 for forming a casting 13 (FIG. 3) such acylinder head or an automobile engine block. Typically, casting coresare received or placed within the molds or dies so as to create hollowcavities and/or casting details or core prints within the castings beingformed therewithin. Each of the molds or dies 11 typically can be apermanent mold/die and can be formed from a metal such as cast iron,steel or other materials and having a clam-shell style design for easeof opening and removal of the castings therefrom. The molds also caninclude “precision sand mold” type molds generally formed from agranular material, such as silica, zircon or other sands, mixed with abinder. The binder is formed of a material that is soluble in one ormore fluids, such as water, steam, organic solvents and the like. Thebinder may be formed of casting salts, containing a significant amountof soda ash, which are soluble in water and steam, phenolic resins,phenolic urethane “cold box” binder materials, or other suitable organicbinder material, which are soluble in certain organic solvents and/orare thermally degradable. The molds and dies also may be semi-permanentsand molds having an outer mold wall formed from a sand and binder, ametal such as steel or a combination or both types of materials, or caninclude investment type castings/dies.

The term “molds” will hereafter be used to generally refer to bothpermanent metal molds and sand type molds, except where a particulartype of die or mold is specifically indicated. It further will beunderstood that the various embodiments of the present inventiondisclosed herein can be used for processing castings in permanent ormetal dies, precision sand type molds, semi-permanent molds, and/orinvestment casting molds, depending on the application.

As FIG. 3 illustrates, each mold 11 generally includes a series ofsidewalls 14, a top or upper wall 16, and lower wall or bottom 17, whichdefine an internal cavity 18 within which the molten metal M isreceived. The internal cavity 18 generally is formed with a reliefpattern for forming the internal features of the castings 13 to beformed within the molds so as to define the shape or configuration ofthe finished castings. A pour opening 19 generally is formed in theupper wall or top 16 of each mold and communicates with internal cavity18 to enable the molten metal M to be poured or otherwise introducedinto the mold as indicated in FIGS. 1 and 2. The resultant casting hasthe features of the internal cavity of the mold, with additional coreapertures or access openings 21 also being formed therein where the sandcores are positioned within the molds.

A heating source or element, such as a heated air blower or othersuitable gas-fired or electric heater mechanism, or fluidized bed, 22also generally is provided adjacent the pouring station 12 forpreheating the molds 11. Typically, the molds are preheated to a desiredtemperature depending upon the metal or alloy used to form the casting.For example, for aluminum, the molds would be preheated to a range ofapproximately 400-600° C. Other varying preheating temperaturesgenerally will be required for preheating various different metallicalloys or metals for forming the castings are well known to thoseskilled in the art and can include a wide range of temperatures aboveand below 400-600° C. Additionally, some mold types may require lowerprocess temperatures to prevent mold deterioration during pouring andsolidification. In such cases, such where the metal processingtemperatures are required to be higher, a suitable metal temperaturecontrol method, such as radiant or induction heating, can be employed toaccomplish the process specified herein.

Alternatively, the molds can be provided with internal heating sourcesor elements for heating the molds. For example, for embodiments in whichthe castings are being formed in permanent type metal dies, the dies caninclude cavities or passages formed adjacent the casting and in which aheated fluid medium such as a thermal oil is received and/or circulatedthrough the dies for heating the dies. Thereafter, thermal oils or othersuitable media can be introduced and/or circulated through the dies,with the oil being of a lower temperature, for example 250° C.-300° C.,to cool the castings and cause the castings to solidify. A highertemperature thermal oil, for example, heated to approximately 500°C.-550° C., then typically will be introduced and/or circulated throughthe dies to arrest the cooling and raise the temperature of the castingsback to a soak temperature for heat treating the castings in their dies.The pre-heating of the dies and/or introduction of heated media into thedies causes the dies to function as heat treatment units and helpsmaintain the metal of the castings at or near a heat treatmenttemperature so as to minimize heat loss as the molten metal is pouredand solidifies in the dies and thereafter are transferred to asubsequent processing station for heat treatment.

As indicated in FIG. 1, once the molten metal or metallic alloy has beenpoured into the mold and has at least partially solidified into acasting, the mold and casting generally are removed from the pouringstation 12 by a mold transfer mechanism 25, and are transferred to aloading station 26. The mold transfer mechanism can include a dietransfer robot (not shown), winch or other type of conventionally knowntransfer mechanism for moving the molds from the pouring station to theloading station located in close proximity to the pouring station. In afirst embodiment of the invention, after the molten metal M hassolidified within the mold to form the casting, the casting 13 (FIG. 3)is removed from its mold 11 prior to or at the loading station 26 (FIG.1), such as by a robotic arm or similar mechanism, and is placed withina saddle 27 in a predefined, indexed position with its x, y, and zcoordinates known. As a result, the core apertures 21 (FIG. 3) of thecastings likewise are oriented or aligned in known positions for removalof the sand cores from the castings.

As FIG. 3 illustrates, each saddle generally is a basket or carriertypically formed from a metal material and having a base 28 and a seriesof side walls 29 so as to define an open casting chamber or receptacle31 in which one or more castings 13 are received with the core aperturesor access openings thereof exposed. The castings are generally fixed intheir known indexed or registered orientation or position when placedwithin the receptacle 31 of their saddle 27. The saddles further can beof a variety of sizes to accommodate multiple castings therein fortransport, with each of the castings contained therein being maintainedin a predefined, indexed position as indicated in FIG. 3. In addition,as indicated in FIG. 3, the saddles 27 can further include locatingdevices 32 mounted to the base and/or walls 28 and 29 of each saddle forguiding and maintaining the castings into their desired, indexedpositions within the saddles 27.

The locating devices can include guide pins 33, such as shown in FIG. 3,or can include notches or grooves, such as indicated by dashed lines 34in FIG. 3 or other, similar devices for guiding or directing thecastings into a desired indexed position or orientation. Typically, theguide pins 33 will be formed from a metal material such as cast iron orsimilar material having a high heat resistance, and are mounted to thebase or any of the sidewalls of the saddle. Corresponding locator orguide openings 36 (shown in dashed lines) generally are formed in thecasting during the casting process, such as by the use of guide pinsmounted to the bottom or side walls of the molds, or through the use ofdegradable sand core-type materials. As the castings are placed withintheir saddles, the guide pins are received within the correspondingguide openings of the castings so as to locate and maintain the castingsin their desired, indexed positions having known, defined x, y and zcoordinates, with the positions of the core access openings of thecastings likewise oriented or aligned at known positions to enable moreefficient and direct application of heat to the sand cores within thecastings to enhance the dislodging and removal of the sand material forreclamation.

In addition, in certain applications, the molds may include a steel oriron “chill” or insert having various design features of the castingimparted thereon for improved grain structure of the casting. Thesechills can be either removed after pouring or can be left with andremain part of the casting upon solidification of the molten metal ofthe casting. The chills, if left in the casting, also can be used aslocating devices to enable the castings to be located within theirsaddles in their desired alignment or position. The features or detailleft by the removal of the chill can also act as a locating point forengagement of a guide pin or other locating device within the saddle soas to hold each casting in its desired, indexed position.

As indicated in FIG. 1, after each casting 13 has been loaded in itssaddle with the x, y and z coordinates of its position or orientationknown, the castings are then moved in their saddles into and through aheat treatment station 40 for heat treatment, core removal and sandreclamation if desired. The saddles are generally conveyed or movedthrough the heat treatment station on a conveyor or rails so that thecastings are maintained in their known indexed positions as they aremoved through the heat treatment station. The heat treatment station 40generally includes a heat treatment furnace, such as a gas firedfurnace, and generally includes a series of treatment zones or chambersfor heat treating each casting and removal and reclamation of the sandmaterial of the sand cores. Such heat treatment zones can includevarious types of heating environments such as conduction, including theuse of fluidized beds, and convection, such as using heated air flows.Other heating chambers or application means could include induction andradiant heating environments. The number of treatment zones and/orenvironments can be divided into as many or as few number of zones asthe individual applications may require to heat treat and remove thesand cores therefrom, and each casting typically is kept inside its molduntil a saddle is available to move it through a heat treatment station.It is further possible to additionally age the castings within the heattreatment station 40 if so desired.

Examples of a heat treatment furnace or system in which heat treatmentof castings is carried out in conjunction with the removal of the sandcores from the castings, and potentially the reclamation of the sandfrom the sand cores of the castings as well, are illustrated in U.S.Pat. Nos. 5,294,094; 5,565,046; and 5,738,162, the disclosures of whichare incorporated herein by reference. A further example of a heattreatment furnace for the heat treatment of metal castings andin-furnace and sand core removal and sand reclamation that can beutilized with the present invention is illustrated in U.S. Pat. No.6,217,317, the disclosure of which is likewise incorporated herein byreference. Furthermore, U.S. Patent Application Nos. 60/401,969;10/066,383; and, 09/665,354 are hereby incorporated by reference intheir entirety.

As indicated in FIG. 1, the heat treatment station 40 includes a heatand/or fluid source or element 41, here illustrated as including aseries of nozzle stations 42 positioned at spaced intervals along thelength of the heat treatment station to enhance the heat treatment andsand core removal from the castings. The number of nozzle stationspositioned along the heat treatment station can vary as needed,depending upon the core print or design of the casting. Each of thenozzle stations or assemblies 42 includes a series of nozzles 43,mounted and oriented at known or registered positions corresponding tothe known, indexed positions of the castings being passed therethroughin their saddles. The number of nozzles in each nozzle station isvariable, depending upon the core prints of the castings, such thatdifferent types of castings having differing core prints can utilize anoptionally different arrangement or number of nozzles per nozzlestation. The nozzles typically are controlled through a control systemthat can be operated remotely so as to engage or disengage various onesof the nozzles at the different nozzle stations as needed, dependingupon the design or core prints of the castings passing through the heattreatment station.

Each nozzle 43 generally is mounted in a predetermined position and/ororientation, aligned with one of the core apertures or access openingsor core prints or a set of core apertures formed in the castingsaccording to the known, indexed positions or orientations of thecastings within the saddles. Each of the nozzles is supplied with afluid media, typically under high pressure and heated, which includesone or more components in which one or more components of the core aresoluble. For example, the fluid media used may include air, water,steam, thermal oils, other organic solvents and mixtures thereof. Thefluids are directed at the core openings under high pressure, so as todevelop relatively high fluid velocities, typically approximately 1,000FPM to approximately 15,000 FPM, although greater or lesser velocitiesand thus pressures also can be used as required for the particularcasting application. The pressurized fluid flows, streams or blastsapplied to the castings by the nozzles tend to impact or contact thecores within the castings and help heat treat the castings and cause thebinder materials of the sand cores to at least partially dissolve,degrade or otherwise break down. When the core binder materials areexposed to fluid in which it is soluble, it begins to dissolve in thefluid. Dissolution of the binder causes the chemical bonds linking thebinder molecules to each other and to the filler particles to breakdown. Breaking of these chemical bonds tends to weaken the core, therebymaking it even more susceptible to degradation from the heat and forceof impact of the fluid on the core. Thus, when the binder material issoluble in the fluid directed at the core, the core tends to degrade andbecome dislodged from the casting more rapidly than would otherwiseoccur if the fluid impacting the core was not a solvent for theparticular materials contained within the core. Furthermore, solubilitytends to increase with increases in temperature. Thus, if the fluidand/or core is heated the binder material will tend to dissolve evenmore rapidly in the fluid, thereby causing the degradation of the coreto proceed even more rapidly. Accordingly, degradation of the coreresults from one or more in combination of the heat, force and solventcharacteristics of the fluid to which the core is exposed. As the sandcores are broken down or dispersed by the fluid flows, the sand of thesand cores tends to be removed or cleaned from the castings through thecore apertures or access openings with the passage of the fluid flowsthrough the castings for recovery and reclamation of the sand.

The nozzles 43 of each nozzle assembly or station 42, further can beadjusted to different nozzle positions depending upon thecharacteristics of the castings and the pressure of the fluid flows orblasts can also be adjusted. The adjustment of the nozzles can beaccomplished remotely, such as through the use of robotically movable orpositionable nozzles. The fluids from the nozzles also can be applied atdifferent temperatures, depending upon which zones within the heattreatment station of the nozzles from which they are dispensed arelocated, so that the fluid flows will not interfere negatively with theheat treatment process for the castings as they are moved through theheat treatment furnace or station.

In addition, the nozzles of each nozzle station can be moved betweenvarious nozzle positions including moving between a rest position and anapplication position, or between several application positions, orientedtoward and/or aligned with the core apertures or access openings uponmovement of the castings into different zones or stations within theheat treatment station so as to strategically direct high pressure flowsof a heated fluid media toward the different core apertures or accessopenings to cause the sand cores and/or sand molds to be broken up anddislodged from the castings for removal of the sand cores therefrom.Thus, the use of the nozzle stations within the heat treatment furnaceor station enhances and enables a more efficient breakdown and removalof the sand cores from each casting during heat treatment of thecastings, and can assist in the reclamation of the sand materials fromthe sand cores for reuse.

As indicated in FIG. 1, after the heat treatment and core removal foreach casting has been completed, each casting is removed from the heattreatment station 40 and typically is moved into a quenching station 45.The quenching station 45 typically includes a quench tank filled with acooling fluid, such as water or other known material in which eachcasting is immersed for cooling and quenching. The capacity and size ofthe quench tank generally is a function of the castings being formed andthe specific heat of the metal or metal alloy comprising the castingsand the temperatures to which each casting has been heated.Alternatively, the quenching station can include one or a series ofnozzles for applying cooling fluid to the castings for quenching and/orfurther binder degradation and core removal.

An additional embodiment of the present invention illustrating thein-mold heat treatment of castings is illustrated in FIGS. 4-8B. Asillustrated in FIG. 4, in this embodiment of a casting process 50, amolten metal or alloy M is poured into a die or mold 51 at a pouring orcasting station 52. As indicated in FIGS. 4-5B, the dies/molds, 51 inthis embodiment typically include permanent or semi-permanent diesformed from a metal such as cast iron, steel, or similar material (FIGS.4-5B) or can be sand or precision sand molds formed from a sand materialmixed with an organic binder as is known in the art. Less frequently,molds are made for investment casting in which the mold is comprised ofa ceramic coating shaped by a pattern. The molds generally include sidesections or shells defining an internal chamber 53 within the dies andin which the molten metal is received for forming castings 54. Each ofthe molds 51 further generally includes a sand core 55, as illustratedin FIG. 4, generally formed from a sand material mixed with an organicbinder for forming bores and or core apertures or access openings in thecastings formed within the molds and for creating casting details orcore prints. The dies or sand molds 51 in this embodiment, furthertypically include ports or access openings 56 (FIG. 4-5B) that areformed at selected, desired positions or locations about the molds andextend through the side walls of 57 of the dies or sand molds 51 so asto provide access to the castings 54 being formed therewithin for directapplication of heat to the castings while in-mold and for dislodging andremoval of the sand cores therefrom. A heating source or element such asa heated air blower, fluid nozzle, fluid bed, or other suitablegas-fired or electric heater mechanism 58 (FIG. 4) also can be providedadjacent the pouring or casting station 52 for preheating the dies orsand molds as the molten material M is introduced therein.

Alternatively, the permanent metal dies can be formed with cavitiesadjacent the castings within the dies, in which a heated gas, steam,water, organic solvent, thermal oil or other heated medium can bereceived and/or circulated through the dies for preheating the dies andenabling the dies to function as a heat treatment unit, heating thecastings within the dies. Various areas of the permanent dies furthercan be heated or cooled variably to enable variations in the desiredmechanical properties of the castings formed therein, such as increasedtoughness or elongation properties, along desired areas of the castings.Typically, the permanent metal dies are preheated to a desiredtemperature depending upon the heat treatment temperature required forthe metal or alloy being used to form the casting, i.e., 400-600° C. foraluminum. The pre-heating of the permanent metal dies tends tosubstantially maintain and minimize loss of temperature of the castingsbeing formed within the permanent metal dies at or near the heattreatment temperature for the castings as the permanent metal dies aretransferred from the pouring station and to at least partially heattreat the castings as they solidify, and to enhance the heat treatmentof the castings by reducing heat treatment times since the castings donot have to be significantly reheated to raise their temperature tolevels necessary for heat treatment.

Active temperature control of the mold or die also permits carefulcontrol of metal solidification rates within the mold or die. Thus, theprocess may include prescribed, controlled cooling rates for the moltenmetal, such that the metal solidifies, as a whole or in specific areas,to produce optimized metallurgical microstructures in the solid metal.For example, aluminum alloys may achieve higher properties if theSecondary Dendrite Arm Spacing (SDAS) of the solidified metal issufficiently small so as to permit more effective solution of theelements. SDAS is typically determined by the cooling rate of thecasting or specific area of the casting; thus controlling cooling ratesduring solidification with the present invention generally will producethe desired SDAS, and hence improved properties in the casting.

Once each mold 51 has been filled with a molten material M, the moldtypically is transferred from the casting or pouring station 52 by atransfer mechanism 59 into a nearby loading station 61. The transfermechanism 59 generally can include a transfer robot, winch, conveyor,carousel or other type of conventionally known transfer mechanism formoving the molds from the pouring station to the loading station. Thetransfer mechanism positions each mold in a known, indexed position atthe loading station, with the x, y and z coordinates of the dies beinglocated in a known orientation or alignment prior for heat treatment.

In the present embodiment of the invention, the molds thereaftergenerally are moved into a heat treatment station 62 to at leastpartially heat treat the castings and break down their sand cores and/orsand molds for removal. As discussed above, the heat treatment station62 generally includes a heat treatment furnace, typically a gas firedfurnace, having a series of treatment zones or chambers for applyingheat to the dies and thus to the castings, for at least partial heattreatment of the castings “in-die” or in-mold. The heat treatment zonescan include a variety of different heating environments such asconductive or convection heating chambers, for example, fluidized bedsor forced air chambers, and the number of treatment zones or chamberscan be divided into as many or as few zones as an individual applicationmay require, depending upon the castings being processed. Additionally,following at least partial heat treatment of the castings while in-mold,the castings can be removed from their molds and passed through the heattreatment station for continued heat treatment, sand core removal andpossibly for sand reclamation.

An example of a heat treatment furnace for the heat treatment and atleast partial breakdown and/or removal of the sand cores from thecastings while the castings remain “in-mold”, the continued heattreatment, and/or sand core removal, and possibly reclamation of thesand of the cores, from the castings after removal from their dies, isillustrated in U.S. Pat. Nos. 5,294,994; 5,565,046; and 5,738,162, thedisclosures of which are hereby incorporated by reference. A furtherexample of a heat treatment furnace for use with the present inventionis illustrated and disclosed in U.S. Pat. No. 6,217,317, the disclosureof which is likewise incorporated herein by reference. These heattreatment furnaces further enable the reclamation of sand from the sandcores of the castings and/or sand molds that is dislodged through thedie access openings during heat treatment of the castings while theyremain in their dies.

The heat treatment station 62 further generally includes a heat source63. In the embodiment illustrated in FIGS. 4-5B, the heat source 63 caninclude a series of nozzle stations 64 or assemblies each equipped witha plurality of nozzles 66. The nozzles of each of the nozzle stations 64generally are oriented at known, preset positions and/or orientations inregistration with the known positions of certain ones or sets of accessopenings 56 of the molds 51. The number of nozzle stations and thenumber of nozzles at each station can be varied as needed for providingheat and/or fluid flows in varying degrees and/or amounts to the diesfor heat treating the castings therewithin to enable control of theheating of the dies and thus the castings, and the adjustment of theheating to different stages of heat treatment of the castings.

Each of the nozzles generally supplies a flow of a heated fluid mediathat is directed toward the molds and typically toward a specific dieaccess opening or set of die access openings of each mold as indicatedin FIGS. 5A and 5B. The fluid medium applied to the molds typicallyincludes heated air, water, steam, thermal oils, organic solvents, ormixtures thereof, or other conventionally known fluid media that aresupplied under high pressure and at varying temperatures to heat themolds, with the temperature of the fluid media flows supplied by thenozzles being controlled to conform to different heat treatment stagesas the casting is passed through the different nozzle stations of theheat treatment station. The introduction of the heated fluid media intothe molds through the access openings further generally tends to causethe core binder to dissolve so as to cause the cores to at leastpartially degrade and be dislodged and/or removed from the castingsduring heat treatment, with the dislodged sand material passing throughthe access openings with the draining of the fluids therefrom. Inaddition, the molds also potentially can be at least partially opened asthey pass through the nozzle stations for more direct application of theheated fluids media to the castings and core openings thereof for heattreatment and sand core removal.

In addition to having the castings pass through a series of nozzlestations that include nozzles mounted in fixed positions in registrationor corresponding to the known positions of the molds, and thus the knownpositions of the access openings, it is further possible to maintain themolds in a fixed casting position at a single nozzle station or at thepouring station for application of heated fluid media thereto. In suchan embodiment, nozzles 66 (FIGS. 5A and 5B) typically are roboticallyoperated so as to be movable between a series of predetermined fluidapplication or nozzle positions as illustrated by arrows 67 and 68 inFIGS. 5A and 5B. As the nozzles 66 move about the molds in the directionof arrows 67 and 68, they apply a heated, pressurized fluid media Fagainst the dies, typically directed toward and into the access openings56, so as to raise and maintain the temperature of the dies at asufficient temperature for heat treating the metal casting therewithinas the molten metal of the castings is solidified. As the metalsolidifies and is brought to the preferred heat treatment temperature,the part may be kept in the mold to complete the heat treatment beforeremoval from the mold and quenching. The various application or nozzlepositions of the movable nozzles generally are determined or setaccording to the known x, y and z coordinates of the molds, and thustheir access openings, at the pouring station or upon the positioning orlocating of the dies at the loading station by the die transfermechanism.

As further alternative, the molds, within their castings therein, can beimmersed in a fluid bed (as indicated at 73 in FIG. 6) such as disclosedin U.S. Pat. Nos. 5,294,994; 5,565,046; and 5,738,162), the disclosuresof which have been incorporated by reference. The molds and castingswill be immersed in the fluid bed for heat-up, temperature controland/or mold/core sand removal.

The molds 51 of the present invention typically have the ability to beheated up to approximately 450-650° C. or greater depending upon thesolution heat treatment temperatures required for the alloy or metal ofthe casting that is contained or formed therein, and typically arepreheated to a temperature sufficient to enable at least partial heattreatment of the casting immediately after pouring of the molten metaland to enable controlled solidification of the same while the castingyet resides in the mold or die. The heating of the molds further iscontrolled through control of the temperature of the fluid media appliedto the molds so as to heat and maintain the molds at the desiredtemperatures needed for heat treating the metal of the castings beingformed therein to minimize heat loss during transfer to the heattreatment station, and thus minimize the amount of reheating required toraise the castings back to their heat treatment temperatures.

Further, it is also possible to carryout the increasing of thetemperature of the dies or sand mold packs for in-die heat treatment ofthe castings, while reducing the potential heat loss transfer betweenthe molten material and mold surfaces, and the atmosphere, by includingan energy or heating source within the mold itself. In such anembodiment, the molds typically are permanent type metal dies formedwith cavities or chambers (indicated by dashed lines 69 in FIGS. 5A and5B) in close proximity to the internal cavity 53 in which the casting isformed. A heated fluid media, such as heated water, steam, thermal oilsor other fluid materials capable of readily retaining heat, is then besupplied to the die structure, such as through the ports or accessopenings 56 (FIGS. 4-5B), received within the internal cavities. Thisintroduction of heated media into the dies tends to increase and helpmaintain the temperature of the casting at a desired level needed forheat treatment.

Various alternative embodiments of heat treatment stations or chambersfor use in the systems of the present invention are shown in FIGS. 6-8,and can be used separately or in conjunction with each other tosupplement or replace the nozzle stations as discussed above withadditional heat treatment chambers having various types of alternative,different heat sources 63, which supply or direct energy toward themolds for raising and maintaining the temperature of the molds at therequired temperature for heat treating the castings therein.

In a first example of a heat treatment chamber 70, illustrated in FIG.6, the molds 51 generally are sand mold packs and are placed on aconveyor or transport mechanism 71 for movement through the heatingchamber 70 as indicated by arrows 72. The heating chamber 70 typicallyis an elongated furnace chamber having an insulated floor, sides, andceiling and, as illustrated in the embodiment of FIG. 6, a fluidized bed73, typically formed from foundry sand and sand dislodged from the coresand sand molds for further degrading of the binder and reclaiming of thesand. In this embodiment, the heat source 63 is a radiant energy source74, typically mounted in the ceiling of the heating chamber 70, althoughit will be understood by those skilled in the art that the radiantenergy source can also be mounted in side walls. In addition, multipleradiant energy sources can be used, mounted in the side walls, overheadand/or below the molds as they are moved through the heating chamber 70on the conveyor or transport mechanism. An example of a radiant energysource will be a infrared emitter or other known type of radiant energysource.

The radiant energy source generally will direct radiant energy atapproximately 400-650° C. toward the dies passing through the heatingchamber, typically being directed against the sides and/or top of eachmold as illustrated by arrows 74. The molds, and thus the castingstherewithin, are subjected to the radiant energy source for a desiredlength of time, depending upon the metal of the castings being heattreated. The radiant energy generally is absorbed by the molds, causingthe temperature of the molds to correspondingly increase so as to heatthe molds and thus the castings therewithin from the outside to theinside of the molds.

FIG. 7 shows a further alternative heating chamber 80 for use in the inmold heat treatment of the present invention, typically for use withsand mold packs formed from sand and a combustible binder. As shown inFIG. 7, the heating chamber 80 generally is an elongated furnace havingan insulated floor, ceiling and sides and includes a conveyor or othertransport mechanism 81 for moving the molds, with their castingstherewithin, through the heating chamber 80 in the direction of arrows82. The heat source 63 of the heating chamber 80 generally includes aninduction energy source 83 for applying induction energy to the moldpacks, and thus to the castings and sand cores 54 and 55 containedtherewithin and can include a fluid bed along its floor for collectionand reclamation of sand dislodged from the sand cores and sand molds.

The induction energy source generally can include a conduction coil;microwave energy source or other known induction energy sources orgenerators, and, as with the radiant energy source of FIG. 6, can bepositioned in the ceiling of the heating chamber 80, above the molds,along the sides of the heating chamber, or both. The induction energysource will create a high energy field of waves, indicated by arrows 84,that are directed toward the top and/or sides of the molds 51 and are ofa particular frequency or frequencies that will be absorbed by the sandcores 55 so as to cause the temperature of the sand cores and thus thecastings to be increased to correspondingly heat treat the metalcastings within the mold packs by heating the casting and thus the moldsfrom the inside out.

Still a further alternative construction of a heating chamber 90 for usein the present invention for heat treatment of the castings while“in-mold” by adding energy to the molds and thus the castings toincrease the temperature thereof is shown in FIGS. 8A and 8B. In thisembodiment, the molds typically will comprise sand molds formed fromsand and a combustible binder. As shown in FIGS. 8A and 8B, the heatingchamber 90 typically is an elongated autoclave or similar heatingchamber operating under high pressures or vacuums, and includes aconveyor or transport mechanism 91 for conveying the molds 51 with theircastings 54 contained therein in the direction of arrows 92. As themolds and castings are moved through the autoclave heating chamber 90,they generally are passed through a pressurized, low velocity oxygenchamber 93 in which an enriched oxygenated atmosphere is present.

The oxygen chamber generally includes a high pressure, upstream side 94and a low pressure, downstream side 96 that are positioned opposite eachother so that a flow of oxygen is passed therebetween. Typically, thecastings and molds will enter the autoclave heating chamberapproximately at atmospheric pressure. As the molds pass through the lowvelocity oxygen chambers of the autoclave heating chamber 90, thepressure in the chamber is increased and the flow of heated oxygen gasis directed at and is forced through the mold packs, as indicated byarrows 97 (FIG. 8A) and 97′ (FIG. 8B). As a result, the oxygen flow isdriven into and through the molds and to the inner cores of thecastings.

As shown in FIGS. 8A and 8B, the pressurized low velocity oxygen chambercan be oriented in either a vertical orientation (shown in FIG. 8A) or asubstantially horizontal orientation (shown in FIG. 8B) for forcing thehot oxygen gasses through the mold packs, depending upon size and spaceconfigurations for the heating chamber.

As indicated in FIG. 8C, the molds further can be formed with or toinclude a vacuum port or opening, indicated by 102, formed along eitherthe upper or lower surfaces of the molds. A suction or vacuum, indicatedat 103, is applied at the port 102 formed in each mold for drawing theoxygen gas into and through or molds. In this embodiment, the molds aregas or air tight and can include a plug (not shown) for sealing the port102, but which can be removed from the port 102 to provide a suction orvacuum point along the molds as the oxygen gas is drawn or flows throughthe molds.

As the oxygen gas 97 is drawn through the molds by the suction 103, apercentage of oxygen is combusted with the binder material of the sandmolds and/or sand cores, so as to enhance the combustion of the bindermaterial within the heating chamber to provide a heat source for heatingthe castings. As a result, the molds and their castings are furthersupplied with heat energy from the enhanced combustion of the bindermaterial thereof and the oxygen gas, which thus acts as a heat source toincrease the temperature of the castings in the mold packs, while at thesame type breaking down the binder of the molds and/or sand cores forease of removal and reclamation.

It further will be understood that the various heat treatment chambersillustrated in FIGS. 6-8C can either be used separately, or can bemounted or positioned in a series along a heat treatment station or unit105 (FIG. 9), defining separate stations or separate chambers thereof,for enhanced or increased breakdown and removal of the sand cores andsand molds from the castings. As shown in FIG. 9, a radiant energy heattreatment chamber 70 (FIG. 6) can be mounted or positioned at anupstream end 106 (FIG. 9) of the heat treatment unit 105. As the molds,with their castings therein are introduced into the heat treatment unit105, they are received and initially passed through the heating chamber70 and a radiant energy source therein. The radiant heating chamber 70generally heats the molds to a temperature sufficient to initiate thecombustion of the binder of the molds while the same time heating thecastings therewithin to begin the heat treatment of the castings whilestill in-mold.

A further heating chamber 80, having an induction energy source therein,generally will be positioned downstream from the radiant heating chamber70.

The heating chamber 80 will apply induction energy via a high energyfield of electromagnetic waves as discussed above, which generally willtend to further promote the combustion of the binder and heat treatmentof the castings within the molds. In addition, the application of theinductive energy waves will tend to cause cracking or breaking of thesand molds into sections or pieces to further promote the breakdown ofthe sand molds.

Thereafter, an oxygen heating chamber 90, such as shown in FIGS. 8A-8C,will be positioned downstream from heating chamber 80. As the sand moldsare passed into and through the heating chamber 90, the forced flow ofoxygen through the chamber promotes and enhances the combustion of thesand molds and sand cores. As a result, with the binder of the sandmolds having been raised to a combustion temperature and the moldsbecoming cracked in the heating chambers 70 and 80, and/or piecesthereof becoming broken or dislodged, the further enhancement of thecombustion of the binder of the sand cores within the oxygen heatingchamber 90 tends to promote the increased breakdown and dislodging ofthe sand molds and sand cores form the castings. Consequently, the timerequired for breakdown and removal of the sand molds and sand cores isdecreased so that the castings are more rapidly exposed directly to theheating environment of the heat treating unit, while at the same time,the rapid breakdown and combustion of the binder of the sand moldsfurther enhances the heating of the castings to their solution heattreatment temperatures.

As a result of applying energy to the molds themselves, the molds areheated to desired temperatures and can be maintained at a. suchtemperatures as needed for heat treating the castings being formedtherewithin as the molten metal of the casting is solidified within themolds. Such in-mold heat treatment of the castings can significantly cutthe processing time required for heat treating castings, for example, toas low as approximately 10 minutes or less, as the metal of the castingsis generally elevated and stabilized at the heat treatment temperatureshortly after pouring of the molten metal material into the molds. Thus,the heat treatment of the castings can take place in a relatively shortperiod of time following the pouring of the molten metal material intothe molds. The raising of the temperature of the molds to the heattreatment temperature for heat treating the castings further enhancesthe breakdown and combustion of the combustible organic binders of thesand cores and/or sand molds, if used, so as to further reduce the timerequired for the heat treatment and dislodging and reclamation of thesand cores and sand molds of the casting process.

Following the heat treatment of the castings in their molds within theheat treatment station 62, the castings typically are removed from theirmolds and can be moved to an additional heat treatment station forcompletion of the heat treatment of the castings, as needed, and forsand core removal and possible reclamation of the sand materials of thecores. The castings are then moved into a quenching station 110 forquenching and cooling of the castings. Alternatively, as shown in FIG.4, the castings can be removed from their dies and transferred directlyto the quenching station. The quenching station 110 typically includes aquench tank having a cooling fluid such as water or other known coolantmaterial, but the quenching station can also comprise a chamber havingone or a series of nozzles, indicated at 111 in FIG. 4, that applycooling fluids such as air or water to the castings. The quenching alsocan take place in contiguous ancillary quenching equipment that is inclose proximity to the pouring station so that cycle time and heatvariations can be minimized for the setting and treatment of the moltenmetal material of the castings within the molds.

After heat treatment and sand removal of the castings is completed, thecastings can be removed from the molds and transferred to the quenchtank of the quench station for cooling the castings before furtherprocessing, and sand removed from the castings then can be reclaimed forlater reuse. In addition, as indicated in dashed lines in FIG. 4, it isalso possible to transfer the casings directly from the pouring stationto the quenching station. For example, where the molds from the pouringstation are heated to a heat treatment temperature at or adjacent thepouring station for in-mold heat treating the castings, the treatedcastings thereafter can be transferred directly to the quenchingstation.

FIGS. 10A and 10B illustrate still a further embodiment 200 of thepresent invention for the enhanced heat treatment and breakdown andremoval of sand cores and/or sand molds from a series of castings 201.In this embodiment, a molten metal or metal alloy M (FIG. 10A) is pouredinto a mold, such as a cast iron or other permanent type die or asemi-permanent or precision sand mold 202 at a pouring or castingstation 203. The molds generally include an internal cavity 204 in whichthe molten metal is received and solidified to form the casting 201 andin which a sand core 206 typically is provided for forming ports orother interior detail for the casting. Typically, the molds in thisembodiment will also include a series of ports or mold access openings207 that extend through the side walls 208 of the molds. These portsprovide an access to the interior cavity or chamber 204, and thus thecasting being formed therein, for direct application of heat to thecastings while “in-mold” and for assistance in dislodging and removal ofthe sand cores 206 therefrom.

The castings thereafter are removed from the casting or pouring station203 by a transfer mechanism 210, which transfers the molds with theircastings therewithin or which first removes the castings and thereaftertransfers the castings individually to an inlet conveyor or loadingstation, indicated by 211 in FIG. 10A, for a heat treatment line or unit212. The transfer mechanism can include a crane or robotic arm 213, asillustrated in FIG. 10B, including a gripping or engaging portion 214that is adapted to engage, grip and lift the molds and/or castings andis mounted to one end of a body or articulateable arm that is movablyattached to a base portion 214. The crane or arm 213 thus is moveablebetween a transfer position at the pouring station and the inlet 211 ofthe heat treatment unit or line 212 as indicated in FIG. 10A. It will,however, be understood by those skilled in the art that various othersystems or devices for transferring the castings from the pouringstation to the heat treatment line also can be used, such as an overheadcrane, winch, conveyor, hoist, carousel, push rods and other knownmaterial handling devices. The transfer mechanism 210 will position themolds or castings themselves at the inlet or loading station of the heattreatment line with the molds or castings being located in a known,indexed position with their X, Y and Z coordinates in a knownorientation or alignment prior to heat treatment. In some embodiments,as discussed above, this can include locating or mounting the castingsor molds on locator devices such as depositing one or more castings in asaddle having pins, walls and/or other types of locator devices thereinso as to locate and fix the position of the molds or castings within thesaddles.

Thereafter with the molds and/or castings located in their known,desired positions, the molds and/or castings will be introduced into aprocess temperature control station or pre-treatment chamber 218 priorto introduction into the heat treatment furnace 219 of the heattreatment unit 212. Generally, during the transition or transfer of thecastings from the pouring station to the heat treatment line, thecastings will be permitted to cool a sufficient amount as is necessaryfor the molten metal within the molds to solidify and harden to form thecastings. However, as the metal of the castings is cooled below thepoint at which it has solidified, it reaches a process controltemperature below which the time required to both raise the temperatureof the metal of the castings back up to a solution heat treatmenttemperature and for performing the heat treatment thereof issignificantly increased. This process control temperature generallyvaries depending upon the metal and/or metal alloy being used to formthe casting, generally ranging from temperatures of approximately 400°C. or lower for some metals or alloys such as aluminum/copper alloys, upto approximately 1000° C.-1300° C. or greater for other metals or alloyssuch as iron and steel. For example, for aluminum/copper alloys, theprocess control temperature can generally range from about 400° C. toabout 470° C., which temperatures generally fall below the solution heattreatment temperatures for most aluminum/copper alloys, which insteadrange from approximately 475° C. to approximately 490° C. andoccasionally higher.

It has been discovered that when the metal of a casting is permitted tocool below its process control temperature, it generally is necessarythereafter to heat the casting for an additional time, such asapproximately an additional 4 minutes to or more for each minute thatthe metal of the casting is allowed to cool below its process controltemperature in order to raise and maintain the temperature of the metalof the castings back up to the desired solution heat treatmenttemperature so that heat treatment of the castings can be performed. Asa result, if a casting is permitted to cool below the process controltemperature for the metal thereof for even a short time, the timerequired to process and completely heat treat the castings generallywill be significantly increased. For example, if a casting is permitted.to cool below its process control temperature for approximately 10minutes, it can take as much as 40 minutes or more of additional heattreatment/soaking time at the solution heat treatment temperature forthe metal of the castings in order to properly and completely heat treatthe casting. In addition, in a batch processing system wherein thecastings are one of several that are loaded into a basket or tray forprocessing numerous castings in a batch at a single time, it generallyhas been necessary to heat treat the entire batch of castings for a timeand to an extent necessary to completely heat treat the casting(s) withthe lowest temperature. This accordingly will require that the majorityof the castings in the batch will be subjected to heat treatment for asignificantly longer period of time than required to ensure completetreatment of all castings in the batch, thus resulting in wasted energyand increased processing times for the castings.

As indicated in FIGS. 10A and 10B, the process temperature controlstation 218 generally is an elongated tunnel or unit having side walls221, a ceiling 222 and a floor or bottom 223 through which a conveyor orsimilar transport mechanism 224 is extended for conveying the moldsand/or castings therethrough.

The ceiling 222 and sides 221 of the process temperature control station218 generally are formed from or have applied thereto a radiant materialsuch as a metal, metal foil, ceramic or other types of compositematerials that radiate or direct heat inwardly toward the castings so asto thus define a radiant chamber 226 within the process temperaturecontrol station.

A series of heat sources 227 generally are mounted in the ceiling and/oralong the side walls of the, process temperature control station so asto direct a flow of heat energy into the chamber 226 to create a heatedenvironment therewithin. The heat sources 227 can include radiantheaters such as infrared or inductive heating elements, conductive,convection, or other types of heating elements, including the use ofnozzles that spray a heated fluid media, such as air, water, steam,thermal oils and the like, about the molds and/or castings. The processtemperature control station 218 further generally includes an inlet orupstream end 228 and a downstream or outlet end 229, each of which caninclude a sliding door, curtain or similar closure device 231.

As the molds and/or castings are received through the inlet end 228 ofthe process temperature control station, the cooling of the castings isarrested by the application of heat from heat sources 227. Thereafter,the castings are generally maintained at or above their process controltemperature, which temperature generally varies depending upon the metalused to form the castings until the castings are introduced into theheat treatment furnace 219. As a result, the castings are permitted tocool sufficiently to allow the metal thereof to solidify, while thecooling of the castings is arrested at or above the process controltemperature. As a result, the castings are introduced into the heattreatment furnace, they can be more efficiently and rapidly brought totheir solution heat treatment temperatures and subjected tosubstantially complete heat treatment more efficiently.

In addition, as indicated in FIG. 10B, an additional heat source orheating element 232 can be mounted above the inlet 211 for the heattreatment line 219 so as to apply heat to the castings as they aredeposited onto the heat treatment line and are: introduced into theprocess temperature control station. It is also possible to mount a heatsource such as a radiant heater, convection, conduction or other heatingelement on the transfer mechanism itself, or along the path of travel233 (FIG. 10A) of the castings so as to apply heat to the castingsduring the transfer of the castings from the pouring station to the heattreatment line.

Typically, as illustrated in FIGS. 10A and 10B, the castings and/ormolds with the castings therein will be passed from the processtemperature control station directly into the heat treatment furnace 219of the heat treatment line. The heat treatment furnace generally willcomprise a heat treatment furnace or station as discussed above withrespect to the embodiments of FIGS. 1 and 4. An example of such a heattreatment furnace for heat treatment and at least partial breakdownand/or reclamation of the sand cores and/or sand molds from the castingsis illustrated in U.S. Pat. Nos. 5,294,994; 5,565,046; 5,738,162, and6,217,317, the disclosures of which have previously been incorporated byreference.

As discussed above, the heat treatment furnace generally includes aseries of treatment zones, chambers or stations, indicated by 236 inFIG. 10A, for applying heat to the molds and/or castings for heattreatment of the castings. As the castings are moved through these heattreatment zones in their molds, the castings can be heat treated whileat least partially “in-mold”, while at the same time the sand molds inwhich the castings are contained can be rapidly broken down and removedfrom the castings and the sand materials thereof reclaimed. The heattreatment zones or chambers also can include a variety of differentheating environments such as conductive or convection heating chambers,radiant heating chambers or chambers in which an enhanced or negativeair pressure draws a flow of oxygen through the sand molds of thecastings to enhance the combustion of the binders of the sand molds. Theheat treatment furnace further can be divided into as many or as fewtreatment zones as an individual application may require depending uponthe castings being processed.

After passing through the heat treatment furnace 219, the castingsthereafter generally are removed from the heat treatment furnace and canbe transported to a quench station 240 (FIG. 10A) for quenching orfurther processing.

Accordingly, the present invention enables the reduction or eliminationof a requirement for further heat treating of the castings once removedfrom the molds, which are heated to provide solution heating time andcooled to provide the quenching effect necessary, while in-mold, so asto significantly reduce the amount of heat treatment/processing timerequired for forming metal castings.

The present invention further enables an enhanced or more efficient heattreatment and breakdown and removal of sand cores within the castings bydirecting fluid flows at the castings at preset positions, correspondingto known orientations or alignments of the castings and/or the moldswith the castings contained therein as they are passed through a heattreatment station.

It will be understood by those skilled in the art that while the presentinvention has been discussed above with reference to preferredembodiments, various additions, modifications and changes can be madethereto without departing from the spirit and scope of the invention asset forth in the following claims.

1. A method of processing a casting comprising: pouring a moltenmaterial into a mold containing a core; solidifying at least a portionof the molten material to form a casting; pre-heating the casting; heattreating the casting; and, degrading at least a portion of the core witha fluid flow.
 2. The method of claim 1, further comprising opening themold to expose the casting to a pre-heating environment.
 3. The methodof claim 1, further comprising removing the casting from the mold. 4.The method of claim 1, wherein the casting is maintained in a closedmold during pre-heating.
 5. The method of claim 1, wherein pre-heatingthe casting includes exposing the casting to energy selected frominductive energy, radiant energy and combinations thereof.
 6. The methodof claim 1, further comprising directing fluid flows at the casting froma series of nozzles.
 7. The method of claim 6, further comprisingaligning the series of nozzles with openings in the casting.
 8. Themethod of claim 1, wherein the fluid flow comprises a fluid mediaselected from air, water, steam, organic solvents, thermal oils andcombinations thereof.
 9. The method of claim 8, wherein the fluid flowis heated.
 10. The method of claim 1, wherein the core comprises abinder that is soluble in the fluid flow.
 11. The method of claim 1,wherein the casting is exposed to energy selected from inductive energy,radiant energy and combinations thereof during heat treating.
 12. Themethod of claim 1, further comprising quenching the casting.
 13. Themethod of claim 12, wherein quenching comprises exposing the casting toa fluid flow to degrade the core.
 14. The method of claim 13, whereinthe core comprises a binder that is soluble in the fluid flow.
 15. Themethod of claim 14, wherein the fluid flow comprises water, air, steam,organic solvents, thermal oils and combinations thereof.
 16. The methodof claim 1, further comprising aging the casting.
 17. The method ofclaim 1, further comprising adjusting the temperature of the mold priorto pouring the molten material therein.
 18. The method of claim 17,wherein adjusting the temperature of the mold includes heating the die.19. The method of claim 17, wherein adjusting the temperature of themold includes cooling the die.
 20. A method of processing a castingcomprising: pouring a molten material into a mold containing a core;solidifying at least a portion of the molten material to form a casting;heat treating the casting while the casting is in the die; and,degrading the core with a fluid flow, wherein the core comprises abinder that is soluble in the fluid flow.
 21. The method of claim 20,wherein the fluid flow comprises air, water, steam, organic solvents,thermal oils and combinations thereof.
 22. The method of claim 20,further comprising pre-heating the casting.
 23. The method of claim 20,further comprising adjusting the temperature of the mold prior topouring molten material therein.
 24. The method of claim 23, whereinadjusting the temperature of the mold comprises heating the mold. 25.The method of claim 23, wherein adjusting the temperature of the moldcomprises cooling the mold.
 26. The method of claim 20, furthercomprising aligning a nozzle with an opening in the casting, wherein thefluid flow is directed from the nozzle.
 27. The method of claim 20,wherein degrading the core with the fluid flow comprises quenching thecasting with the fluid flow.
 28. The method of claim 20, whereindegrading the core with the fluid flow comprises pre-heating the castingwith the fluid flow.